Reading and Understanding the OTS Rankings

What are the OTS Rankings?

The OTS Rankings were developed so that individual cities could compare their city’s traffic safety statistics to those of other cities with similar-sized populations. Cities could use these comparisons to see what areas they may have problems in and which they were doing well in. The results helped both cities and OTS identify emerging or on-going traffic safety problem areas in order to help plan how to combat the problems and help with the possibility of facilitating grants. In recent years, media, researchers and the public have taken an interest in the OTS Rankings. It should be noted that OTS rankings are only indicators of potential problems; there are many factors that may either understate or overstate a city/county ranking that must be evaluated based on local circumstances.

NOTE: City rankings are for incorporated cities only, for local streets in those cities, and do not include numbers of crashes, killed or injured on freeways or other CHP jurisdiction roads which may be within city limits. County Rankings include all crashes, killed and injured within county borders.

How are the OTS Rankings determined?

Collision rankings are based on the Empirical Bayesian (EB) Ranking Method. This method is increasingly used by researchers and statisticians as a means to bring together and give varying weights to many different factors. Previous OTS Collision Rankings used only population and daily vehicle miles traveled as factors, and ranked them separately. The EB Method still uses population and daily vehicle miles traveled, but adds in crash records, crash trends and other weighing factors to arrive at a single, more accurate ranking.

Data for the rankings is taken from several agencies, including the California Highway Patrol (CHP) Statewide Integrated Traffic Records System (SWITRS), California Department of Transportation (Caltrans), California Department of Justice (DOJ) and the Department of Finance (DOF).

DUI arrest totals and rankings are calculated for cities only and are based on rates of non-CHP DUI arrests (Department of Justice data). This is so that local jurisdictions can see how their own efforts are working.

Counties are assigned statewide rankings, while cities are assigned population group rankings.

IMPORTANT NOTE #1: The figures in the ranking column show as two numbers divided by a slash. The first number is that city’s ranking in that category. The second number is the total number of cities/counties within that “Group”. For instance, if you see “22/56”, that means that city ranks 22nd out of 56 cities of similar size.

IMPORTANT NOTE #2: Number 1 in the rankings is the highest, or “worst.” So, for Group B, a ranking of 1/56 is the highest or worst, 27/56 is average, and 56/56 is the lowest or best.

Headings

Type of Collision – This column delineates the different types of collisions OTS has chosen to show in the rankings. These represent the types with larger percentages of total killed and injured and areas of focus for the OTS grant program.

Victims Killed and Injured – This column shows the number of fatalities and injuries aggregated. Damage-only or fender-bender collisions are not included.

Ranking – This column shows what ranking that city has as compared to other comparably sized incorporated cities in California for that particular type of collision. The first number is that city’s ranking for that type of collision. The second number is the total number of cities/counties within that population grouping.

Types of Collisions

Total Fatal and Injury – The total number of victims involved in all collisions where there were fatalities and/or injuries in that city/county.

Alcohol Involved – Collisions in which there were victims killed or injured where a party (driver, pedestrian, bicyclist) was classified as “Had Been Drinking.”

Had Been Drinking Driver <21 – Collisions in which there were victims killed or injured where a driver who was under the age of 21 had been drinking.

Had Been Drinking Driver 21-34 – Collisions in which there were victims killed or injured where a driver who was between the ages of 21 and 34 had been drinking.

Motorcycles - Collisions in which there were victims killed or injured and a motorcycle was involved.

Pedestrians - Collisions in which there were victims killed or injured and a pedestrian was involved.

Pedestrians <15 - Collisions in which there were victims killed or injured and a pedestrian under the age of 15 was involved.

Pedestrians 65+ - Collisions in which there were victims killed or injured and a pedestrian age 65 and older was involved.

Bicycles - Collisions in which there were victims killed or injured and a bicyclist was involved.

Bicycles <15 - Collisions in which there were victims killed or injured and a bicyclist under age 15 was involved.

Composite – Figures which show rankings only, an aggregate of several of the other rankings (Had Been Drinking 21-34, Had Been Drinking Under21, Alcohol Involved, Hit & Run, Nighttime and Speed collisions). These figures are a means to give an indication of over-all traffic safety.

Speed Related – Collisions in which there were victims killed or injured where speed was the primary factor.

Nighttime (9:00pm - 2:59am) – Collisions in which there were victims killed or injured that occurred between those hours, which are prime hours for DUI, speeding and drowsy driving crashes.

Hit and Run – Collisions in which there were victims killed or injured and a driver left the scene.

*DUI Arrests – DUI arrest figures are shown for cities only, not counties. The number of cities ranked against may be different than from the number of cities in the other categories. Not all cities report DUI arrests to the Department of Justice.